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MIC5231
Micropower Cap LDO Regulator
General Description
The MIC5231 Cap low dropout voltage regulator is intended for low output current biasing applications. It features extremely low ground current, not greater than 4A under all load and temperature conditions, making it efficient and ideal for keep-alive applications in devices such as notebook computers. The MIC5231 offers better than 2% initial accuracy and low dropout (typically 150mV at 10mA output current). An output capacitor is not required for stable operation, decreasing cost and board space. Tiny ceramic chip capacitors may be used to improve transient response. The MIC5231 also features a control pin which allows the regulator to be shut down when not required. Its shutdownstate draws zero current, benefiting battery-powered applications. The MIC5231 is available in fixed output voltages of 2.75V, 3.0V, 3.3V and 5V in the small SOT-23-5 IttyBitty(R) package. Contact Micrel for other voltage options. Data sheets and support documentation can be found on Micrel's web site at: www.micrel.com.
Features
* * * * * * * * * Extremely low quiescent current--only 0.65A No output capacitor requirement Stable with ceramic or tantalum capacitors IttyBitty(R) SOT-23-5 surface-mount package 10mA output drive Low 150mV at 10mA dropout voltage Tight load and line regulation Low temperature coefficient Logic-level enable input
Applications
* * * * * * * Real-time clocks SRAM backup Cellular telephones Laptop, notebook and palmtop computers Battery-powered equipment Bar code scanners SMPS post-regulator and DC-to-DC modules
_________________________________________________________________________________________________________
Typical Application
VIN 6V MIC5231-5.0YM5 IN OUT VOU T 5V EN GND
5V Linear Regulator Application
IttyBitty is a registered trademark of Micrel, Inc. Micrel Inc. * 2180 Fortune Drive * San Jose, CA 95131 * USA * tel +1 (408) 944-0800 * fax + 1 (408) 474-1000 * http://www.micrel.com
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Micrel, Inc.
MIC5231
Ordering Information(1)
Part Number MIC5231-2.75BM5 MIC5231-2.75YM5 MIC5231-3.0BM5 MIC5231-3.0YM5 MIC5231-3.3BM5 MIC5231-3.3YM5 MIC5231-5.0BM5 MIC5231-5.0YM5
Notes: 1. Other voltages available. Contact factory for details. 2. Under bar ( ) symbol used to identify Pb-Free device may not be to scale. 3. SOT-23-5 is a RoHS-compliant package. Lead finish is a NiPdAu. Mold compound is Halogen free.
Marking LM2H LM2H
(2)
Voltage 2.75V 2.75V 3.0V 3.0V 3.3V 3.3V 5.0V 5.0V
Temperature Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C
Package 5-Pin SOT-23 5-Pin SOT-23
(3)
Lead Finish Standard Pb-Free Standard Pb-Free Standard Pb-Free Standard Pb-Free
LM30 LM30(2) LM33 LM33(2) LM50 LM50
(2)
5-Pin SOT-23 5-Pin SOT-23(3) 5-Pin SOT-23 5-Pin SOT-23(3) 5-Pin SOT-23 5-Pin SOT-23
(3)
Pin Configuration
MIC5231-5.0BM5 (M5)
MIC5231-5.0YM5 (M5)
Pin Description
Pin Number 1 2 3 4 5 Pin Name EN GND IN OUT NC Pin Function Enable (Input): Active high. Logic high = enable; logic low = shutdown. Do not float. Ground. Supply Input. Regulated Output. Not internally connected.
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MIC5231
Absolute Maximum Ratings(1)
Supply Voltage (VIN) ...................................... -0.6V to +14V Lead Temperature (soldering, 5sec.)......................... 260C Storage Temperature (Ts) .........................-60C to +150C ESD Rating(3) .................................................................. 2kV
Operating Ratings(2)
Supply Voltage (VIN)........................................ 3.5VV to 12V Ambient Temperature (TA) .......................... -40C to +85C Junction Temperature (TJ) ........................ -40C to +125C Thermal Resistance(4)
Electrical Characteristics
VIN = VOUT + 1V; IL = 100A; CL = 0.47F; TJ = 25C, bold values indicate -40C TJ +125C, unless noted.
Symbol VOUT VOUT/T VOUT/VOUT VDO IQ PSRR Enable Input VENL IENL IENH
Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Devices are ESD sensitive. Handling precautions recommended. 4. The maximum allowable power dissipation at any TA (ambient temperature) is PD(max) = (TJ(max) - TA) / JA. The JC of the MIC5231 is 130C/W. Mounted to a standard PC board, the JA is approximately 235C/W. 5. Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. 6. Regulation is measured at constant junction temperature using low duty cycle pulse testing. 7. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1Vdifferential. For outputs below 3.5V, dropout voltage is the input-to-output differential with the minimum input voltage 3.5V. Minimum input operating voltage is 3.5V.
Parameter Output Voltage Accuracy Output Voltage Temperature Coefficient Line Regulation Load Regulation Dropout Voltage, Note 7 Ground Pin Current Ripple Rejection Enable Input Voltage Enable Input Current Enable Input Current
Condition variation from nominal VOUT Note 5 VIN = 6V to 12V IL = 10A to 10mA, Note 6 IL = 1mA IL = 10mA VIN = 6V, IL = 10mA VIN = 12V, IL = 10mA f = 100Hz, IL = 100A VEN = logic low (regulator off) VEN = logic high (regulator on) VENL 0.18V (regulator off) VENH 1.4V (regulator on)
Min -2 -3
Typ
Max +2 +3
Units % % ppm/C
250 0.2 0.2 15 150 0.65 1.1 50 0.4 1.4 1 1 0.18 300 3 4 0.25 1
% % mV mV A A dB V V nA nA
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MIC5231
Typical Characteristics
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MIC5231
Block Diagram
IN OUT
EN
Bandgap Reference
MIC5231 GND
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MIC5231 Thermal Considerations The MIC5231 is not intended for sourcing currents that would cause a large power loss in the device, but since it is not current limited, it is possible to source more than the rated 10mA. At this point, it is important to ensure that the die temperature does not exceed +125C. Power dissipation in the regulator is calculated as follows:
PD = (VIN - VOUT ) IOUT + VIN IGND
Application Information
Input Capacitor A 0.1F (or larger) capacitor should be placed from the IN (supply input) to GND (ground) if there is more than 20cm of wire between IN and the ac filter capacitor or if supplied from a battery. Output Capacitors The MIC5231 does not require an output capacitor for stability. A 1F or larger capacitor is recommended between OUT (output) and GND to improve the regulator's transient response. A 0.1F capacitor can be used to reduce overshoot recovery time at the expense of overshoot amplitude. The ESR (effective series resistance) of this capacitor has no effect on regulator stability, but low-ESR capacitors improve high frequency transient response. The value of this capacitor may be increased without limit, but values larger than 10F tend to increase the settling time after a step change in input voltage or output current. The MIC5231 has no minimum load current; it will remain stable and in regulation with no load (other than the internal voltage divider). This is especially important in real-time clock and CMOS RAM keep-alive applications. Minimum Load Current The MIC5231 does not require a minimum load for proper operation. This allows the device to operate in applications where very light output currents are required for keep-alive purposes. This is important for powering SRAM or Flash memory in low-power modes for handheld devices. Safe Operating Conditions The MIC5231 does not incorporate current limit or thermal shutdown in the design. The output pass element is approximately 15, therefore, when a short occurs from the output to ground, the current is selflimited. The pass element has a positive temperature coefficient, such that when the device gets hot, the output impedance goes up, limiting the current even further. The maximum junction temperature for the device is +125C, and it is important that this is not exceeded for any length of time.
The MIC5231 consumes only 0.65A over load and does not need to consider that contribution in the power dissipation equation, therefore the equation is simplified.
PD = (VIN - VOUT ) IOUT
The MIC5231, in the IttyBitty SOT-23-5 package, has a thermal resistance, junction-to-ambient, of 235C/W. Using this number, the power dissipation capability of that package, without exceeding a +125C junction temperature rating, can easily be calculated.
PD(MAX) = TJ(MAX) - TA JA
PD(MAX) =
125C - TA 235C/W
If the device is being operated at +85C, the maximum power dissipation allowed can easily be determined. PD(MAX) = 125C - 85C 235C/W
PD(MAX) = 170mW
Therefore, the device can only dissipate 170mW maximum. If the MIC5231 is powered off of a 12V source and the output voltage is 3.3V, the maximum output current can be calculated.
PD(MAX) = (VIN - VOUT ) IOUT
170mW 8.7V
170mW = (12V - 3.3V ) IOUT
IOUT =
IOUT = 19.5mA
Therefore, the device can source almost 20mA at an ambient of +85C before the die temperature exceeds +125C.
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MIC5231
Package Information
5-Pin SOT-23 (M5)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser's use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. (c) 2000 Micrel, Incorporated.
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